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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Ant-Inspired Control Strategies for Collective Transport by Dynamic Multi-Robot Teams with Temporary Leaders

January 2020 (has links)
abstract: In certain ant species, groups of ants work together to transport food and materials back to their nests. In some cases, the group exhibits a leader-follower behavior in which a single ant guides the entire group based on its knowledge of the destination. In some cases, the leader role is occupied temporarily by an ant, only to be replaced when an ant with new information arrives. This kind of behavior can be very useful in uncertain environments where robot teams work together to transport a heavy or bulky payload. The purpose of this research was to study ways to implement this behavior on robot teams. In this work, I combined existing dynamical models of collective transport in ants to create a stochastic model that describes these behaviors and can be used to control multi-robot systems to perform collective transport. In this model, each agent transitions stochastically between roles based on the force that it senses the other agents are applying to the load. The agent’s motion is governed by a proportional controller that updates its applied force based on the load velocity. I developed agent-based simulations of this model in NetLogo and explored leader-follower scenarios in which agents receive information about the transport destination by a newly informed agent (leader) joining the team. From these simulations, I derived the mean allocations of agents between “puller” and “lifter” roles and the mean forces applied by the agents throughout the motion. From the simulation results obtained, we show that the mean ratio of lifter to puller populations is approximately 1:1. We also show that agents using the role update procedure based on forces are required to exert less force than agents that select their role based on their position on the load, although both strategies achieve similar transport speeds. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2020
2

Planejamento da qualidade para empresas prestadoras de serviço de transporte coletivo urbano por ônibus / Quality planning for urban collective transport service providers by buses

Alves, Vanessa Teresinha January 2017 (has links)
Esta tese de doutorado parte do reconhecimento da essencialidade dos serviços públicos, em especial aos serviços de transporte coletivo. O objetivo principal é de cooperar com a inovação do processo de planejamento da qualidade do transporte coletivo urbano por ônibus e adequação destes serviços às suas demandas. Para a construção do método de planejamento da qualidade utilizou-se da metodologia construtivista. O framework foi elaborado a partir da combinação dos resultados da pesquisa teórica integrada às necessidades identificadas pela autora no ambiente em análise. As relações propostas foram estruturadas com base no método Quality Function Deployment (QFD), pois o interesse central foi incluir em um mesmo método de planejamento da qualidade, atributos importantes para os clientes usuários do sistema e o gerenciamento dos processos responsáveis pelo desempenho do serviço oferecido. Como forma de avaliar o método proposto, o mesmo foi aplicado em uma empresa prestadora do serviço de transporte coletivo urbano. A principal contribuição do artefato proposto está na ampliação das ações relacionadas à obtenção da qualidade, evidenciando que apenas o conhecimento sobre o nível de satisfação relacionado ao serviço de transporte coletivo urbano não permite oferecer um serviço de qualidade superior às expectativas dos clientes. É necessário adotar padrões de excelência e reconhecer qual a necessidade de investimentos para melhorar a qualidade e a eficiência no serviço de transporte coletivo urbano de forma contínua e sustentada. Através da aplicação, pôde-se concluir que o método atende as necessidades da empresa, servindo como guia para essencial melhoria da qualidade. / This doctoral thesis part of recognition of the essentiality of public services, particularly the collective urban transport services. The main objective is to cooperate with the innovation of quality planning process of urban collective transport by bus and adequacy of these services to their demands. For the construction of the method of projection of the quality it made use of the methodology constructivist. The framework was prepared from the combination of the results of the theoretical inquiry integrated to the necessities identified by the author in the environment in analysis.The proposed relations were structured on basis of the method Quality Function Deployment (QFD), since the central interest included in the same method of projection of the quality, important attributes for the users clients of the system and the management of the processes responsible for the performance of the offered service. Like the form of valuing the proposed method, the same thing was applied in a serviceable enterprise of the service of urbane collective transport. The main contribution of the proposed product is in the enlargement of the actions made a list to getting the quality, showing up that only the knowledge on the level of satisfaction made a list to the service of urbane collective transport does not allow offering a service of quality superior to the expectations of the clients. It is necessary to adopt standards of excellence and the investments necessity will recognize which to improve the quality and the efficiency in the service of urbane collective transport of continuous and supported form. Through the application, it was possible to end that the method attends the necessities of the enterprise, serving as a guide for effective improvement of the quality.
3

Planejamento da qualidade para empresas prestadoras de serviço de transporte coletivo urbano por ônibus / Quality planning for urban collective transport service providers by buses

Alves, Vanessa Teresinha January 2017 (has links)
Esta tese de doutorado parte do reconhecimento da essencialidade dos serviços públicos, em especial aos serviços de transporte coletivo. O objetivo principal é de cooperar com a inovação do processo de planejamento da qualidade do transporte coletivo urbano por ônibus e adequação destes serviços às suas demandas. Para a construção do método de planejamento da qualidade utilizou-se da metodologia construtivista. O framework foi elaborado a partir da combinação dos resultados da pesquisa teórica integrada às necessidades identificadas pela autora no ambiente em análise. As relações propostas foram estruturadas com base no método Quality Function Deployment (QFD), pois o interesse central foi incluir em um mesmo método de planejamento da qualidade, atributos importantes para os clientes usuários do sistema e o gerenciamento dos processos responsáveis pelo desempenho do serviço oferecido. Como forma de avaliar o método proposto, o mesmo foi aplicado em uma empresa prestadora do serviço de transporte coletivo urbano. A principal contribuição do artefato proposto está na ampliação das ações relacionadas à obtenção da qualidade, evidenciando que apenas o conhecimento sobre o nível de satisfação relacionado ao serviço de transporte coletivo urbano não permite oferecer um serviço de qualidade superior às expectativas dos clientes. É necessário adotar padrões de excelência e reconhecer qual a necessidade de investimentos para melhorar a qualidade e a eficiência no serviço de transporte coletivo urbano de forma contínua e sustentada. Através da aplicação, pôde-se concluir que o método atende as necessidades da empresa, servindo como guia para essencial melhoria da qualidade. / This doctoral thesis part of recognition of the essentiality of public services, particularly the collective urban transport services. The main objective is to cooperate with the innovation of quality planning process of urban collective transport by bus and adequacy of these services to their demands. For the construction of the method of projection of the quality it made use of the methodology constructivist. The framework was prepared from the combination of the results of the theoretical inquiry integrated to the necessities identified by the author in the environment in analysis.The proposed relations were structured on basis of the method Quality Function Deployment (QFD), since the central interest included in the same method of projection of the quality, important attributes for the users clients of the system and the management of the processes responsible for the performance of the offered service. Like the form of valuing the proposed method, the same thing was applied in a serviceable enterprise of the service of urbane collective transport. The main contribution of the proposed product is in the enlargement of the actions made a list to getting the quality, showing up that only the knowledge on the level of satisfaction made a list to the service of urbane collective transport does not allow offering a service of quality superior to the expectations of the clients. It is necessary to adopt standards of excellence and the investments necessity will recognize which to improve the quality and the efficiency in the service of urbane collective transport of continuous and supported form. Through the application, it was possible to end that the method attends the necessities of the enterprise, serving as a guide for effective improvement of the quality.
4

Development and Analysis of Stochastic Boundary Coverage Strategies for Multi-Robot Systems

January 2016 (has links)
abstract: Robotic technology is advancing to the point where it will soon be feasible to deploy massive populations, or swarms, of low-cost autonomous robots to collectively perform tasks over large domains and time scales. Many of these tasks will require the robots to allocate themselves around the boundaries of regions or features of interest and achieve target objectives that derive from their resulting spatial configurations, such as forming a connected communication network or acquiring sensor data around the entire boundary. We refer to this spatial allocation problem as boundary coverage. Possible swarm tasks that will involve boundary coverage include cooperative load manipulation for applications in construction, manufacturing, and disaster response. In this work, I address the challenges of controlling a swarm of resource-constrained robots to achieve boundary coverage, which I refer to as the problem of stochastic boundary coverage. I first examined an instance of this behavior in the biological phenomenon of group food retrieval by desert ants, and developed a hybrid dynamical system model of this process from experimental data. Subsequently, with the aid of collaborators, I used a continuum abstraction of swarm population dynamics, adapted from a modeling framework used in chemical kinetics, to derive stochastic robot control policies that drive a swarm to target steady-state allocations around multiple boundaries in a way that is robust to environmental variations. Next, I determined the statistical properties of the random graph that is formed by a group of robots, each with the same capabilities, that have attached to a boundary at random locations. I also computed the probability density functions (pdfs) of the robot positions and inter-robot distances for this case. I then extended this analysis to cases in which the robots have heterogeneous communication/sensing radii and attach to a boundary according to non-uniform, non-identical pdfs. I proved that these more general coverage strategies generate random graphs whose probability of connectivity is Sharp-P Hard to compute. Finally, I investigated possible approaches to validating our boundary coverage strategies in multi-robot simulations with realistic Wi-fi communication. / Dissertation/Thesis / Doctoral Dissertation Computer Science 2016
5

Scalable Control Strategies and a Customizable Swarm Robotic Platform for Boundary Coverage and Collective Transport Tasks

January 2017 (has links)
abstract: Swarms of low-cost, autonomous robots can potentially be used to collectively perform tasks over large domains and long time scales. The design of decentralized, scalable swarm control strategies will enable the development of robotic systems that can execute such tasks with a high degree of parallelism and redundancy, enabling effective operation even in the presence of unknown environmental factors and individual robot failures. Social insect colonies provide a rich source of inspiration for these types of control approaches, since they can perform complex collective tasks under a range of conditions. To validate swarm robotic control strategies, experimental testbeds with large numbers of robots are required; however, existing low-cost robots are specialized and can lack the necessary sensing, navigation, control, and manipulation capabilities. To address these challenges, this thesis presents a formal approach to designing biologically-inspired swarm control strategies for spatially-confined coverage and payload transport tasks, as well as a novel low-cost, customizable robotic platform for testing swarm control approaches. Stochastic control strategies are developed that provably allocate a swarm of robots around the boundaries of multiple regions of interest or payloads to be transported. These strategies account for spatially-dependent effects on the robots' physical distribution and are largely robust to environmental variations. In addition, a control approach based on reinforcement learning is presented for collective payload towing that accommodates robots with heterogeneous maximum speeds. For both types of collective transport tasks, rigorous approaches are developed to identify and translate observed group retrieval behaviors in Novomessor cockerelli ants to swarm robotic control strategies. These strategies can replicate features of ant transport and inherit its properties of robustness to different environments and to varying team compositions. The approaches incorporate dynamical models of the swarm that are amenable to analysis and control techniques, and therefore provide theoretical guarantees on the system's performance. Implementation of these strategies on robotic swarms offers a way for biologists to test hypotheses about the individual-level mechanisms that drive collective behaviors. Finally, this thesis describes Pheeno, a new swarm robotic platform with a three degree-of-freedom manipulator arm, and describes its use in validating a variety of swarm control strategies. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2017
6

Planejamento da qualidade para empresas prestadoras de serviço de transporte coletivo urbano por ônibus / Quality planning for urban collective transport service providers by buses

Alves, Vanessa Teresinha January 2017 (has links)
Esta tese de doutorado parte do reconhecimento da essencialidade dos serviços públicos, em especial aos serviços de transporte coletivo. O objetivo principal é de cooperar com a inovação do processo de planejamento da qualidade do transporte coletivo urbano por ônibus e adequação destes serviços às suas demandas. Para a construção do método de planejamento da qualidade utilizou-se da metodologia construtivista. O framework foi elaborado a partir da combinação dos resultados da pesquisa teórica integrada às necessidades identificadas pela autora no ambiente em análise. As relações propostas foram estruturadas com base no método Quality Function Deployment (QFD), pois o interesse central foi incluir em um mesmo método de planejamento da qualidade, atributos importantes para os clientes usuários do sistema e o gerenciamento dos processos responsáveis pelo desempenho do serviço oferecido. Como forma de avaliar o método proposto, o mesmo foi aplicado em uma empresa prestadora do serviço de transporte coletivo urbano. A principal contribuição do artefato proposto está na ampliação das ações relacionadas à obtenção da qualidade, evidenciando que apenas o conhecimento sobre o nível de satisfação relacionado ao serviço de transporte coletivo urbano não permite oferecer um serviço de qualidade superior às expectativas dos clientes. É necessário adotar padrões de excelência e reconhecer qual a necessidade de investimentos para melhorar a qualidade e a eficiência no serviço de transporte coletivo urbano de forma contínua e sustentada. Através da aplicação, pôde-se concluir que o método atende as necessidades da empresa, servindo como guia para essencial melhoria da qualidade. / This doctoral thesis part of recognition of the essentiality of public services, particularly the collective urban transport services. The main objective is to cooperate with the innovation of quality planning process of urban collective transport by bus and adequacy of these services to their demands. For the construction of the method of projection of the quality it made use of the methodology constructivist. The framework was prepared from the combination of the results of the theoretical inquiry integrated to the necessities identified by the author in the environment in analysis.The proposed relations were structured on basis of the method Quality Function Deployment (QFD), since the central interest included in the same method of projection of the quality, important attributes for the users clients of the system and the management of the processes responsible for the performance of the offered service. Like the form of valuing the proposed method, the same thing was applied in a serviceable enterprise of the service of urbane collective transport. The main contribution of the proposed product is in the enlargement of the actions made a list to getting the quality, showing up that only the knowledge on the level of satisfaction made a list to the service of urbane collective transport does not allow offering a service of quality superior to the expectations of the clients. It is necessary to adopt standards of excellence and the investments necessity will recognize which to improve the quality and the efficiency in the service of urbane collective transport of continuous and supported form. Through the application, it was possible to end that the method attends the necessities of the enterprise, serving as a guide for effective improvement of the quality.
7

Decentralized Control of Collective Transport by Multi-Robot Systems with Minimal Information

January 2020 (has links)
abstract: One potential application of multi-robot systems is collective transport, a task in which multiple mobile robots collaboratively transport a payload that is too large or heavy to be carried by a single robot. Numerous control schemes have been proposed for collective transport in environments where robots can localize themselves (e.g., using GPS) and communicate with one another, have information about the payload's geometric and dynamical properties, and follow predefined robot and/or payload trajectories. However, these approaches cannot be applied in uncertain environments where robots do not have reliable communication and GPS and lack information about the payload. These conditions characterize a variety of applications, including construction, mining, assembly in space and underwater, search-and-rescue, and disaster response. Toward this end, this thesis presents decentralized control strategies for collective transport by robots that regulate their actions using only their local sensor measurements and minimal prior information. These strategies can be implemented on robots that have limited or absent localization capabilities, do not explicitly exchange information, and are not assigned predefined trajectories. The controllers are developed for collective transport over planar surfaces, but can be extended to three-dimensional environments. This thesis addresses the above problem for two control objectives. First, decentralized controllers are proposed for velocity control of collective transport, in which the robots must transport a payload at a constant velocity through an unbounded domain that may contain strictly convex obstacles. The robots are provided only with the target transport velocity, and they do not have global localization or prior information about any obstacles in the environment. Second, decentralized controllers are proposed for position control of collective transport, in which the robots must transport a payload to a target position through a bounded or unbounded domain that may contain convex obstacles. The robots are subject to the same constraints as in the velocity control scenario, except that they are assumed to have global localization. Theoretical guarantees for successful execution of the task are derived using techniques from nonlinear control theory, and it is shown through simulations and physical robot experiments that the transport objectives are achieved with the proposed controllers. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2020
8

Um sistema informatizado de apoio a usuários de transporte coletivo. / An eletronic system to support collective transport users.

Caetano, Daniel Jorge 29 November 2005 (has links)
O principal objetivo deste trabalho foi o desenvolvimento de um sistema informatizado para o auxílio na escolha modal pelos usuários de transporte público. Neste sistema, as alternativas a considerar e soluções geradas devem se basear nas solicitações do usuário e poderão ser usadas para o planejamento tático e/ou estratégico do sistema de transporte considerado. O sistema foi modelado para solução através do algoritmo de fluxo em rede Label Correcting, capaz de lidar com esse problema multimodal, implementado em uma linguagem de programação orientada a objetos. O sistema foi concebido como uma aplicação de internet e, embora seja voltado para um sistema de transporte genérico, foi aplicado e testado com base nas alternativas de transporte disponíveis e malha de ruas da Cidade Universitária Armando de Salles Oliveira. / The main target of this master of science research is the development of a tool to help on modal selection by the public transportation users, which will be implemented as an eletronic information system.Since the infomation must be provided in real time to the user,it is important to the system to be fast and easy to use.It is also a requirement that the system presents options and information to help the user on the selection of the best choice among all possible ones. The alternatives to be considered and generated solutions shall be based on the user requests related to origin and destination of the desired trip. The requests will be stored and could be used for tactic and/or strategic planning of the concerned system of transport. This multimodal problem will be modeled to be solved with the Label Correcting network flow algorithm and implemented using an object oriented language. Although addressed to a generic transport system,it will be implemented and tested based on the available transport alternatives and street mesh of the Cidade Universitaria Armando de Salles Oliveira. The system may be available to users through internet.
9

Um sistema informatizado de apoio a usuários de transporte coletivo. / An eletronic system to support collective transport users.

Daniel Jorge Caetano 29 November 2005 (has links)
O principal objetivo deste trabalho foi o desenvolvimento de um sistema informatizado para o auxílio na escolha modal pelos usuários de transporte público. Neste sistema, as alternativas a considerar e soluções geradas devem se basear nas solicitações do usuário e poderão ser usadas para o planejamento tático e/ou estratégico do sistema de transporte considerado. O sistema foi modelado para solução através do algoritmo de fluxo em rede Label Correcting, capaz de lidar com esse problema multimodal, implementado em uma linguagem de programação orientada a objetos. O sistema foi concebido como uma aplicação de internet e, embora seja voltado para um sistema de transporte genérico, foi aplicado e testado com base nas alternativas de transporte disponíveis e malha de ruas da Cidade Universitária Armando de Salles Oliveira. / The main target of this master of science research is the development of a tool to help on modal selection by the public transportation users, which will be implemented as an eletronic information system.Since the infomation must be provided in real time to the user,it is important to the system to be fast and easy to use.It is also a requirement that the system presents options and information to help the user on the selection of the best choice among all possible ones. The alternatives to be considered and generated solutions shall be based on the user requests related to origin and destination of the desired trip. The requests will be stored and could be used for tactic and/or strategic planning of the concerned system of transport. This multimodal problem will be modeled to be solved with the Label Correcting network flow algorithm and implemented using an object oriented language. Although addressed to a generic transport system,it will be implemented and tested based on the available transport alternatives and street mesh of the Cidade Universitaria Armando de Salles Oliveira. The system may be available to users through internet.
10

Procedimento de AnÃlise do Impacto Ambiental do RuÃdo de TrÃfego em Terminais de Transporte Coletivo Urbano: um estudo de caso no MunicÃpio de Fortaleza / PROCEDURE OF ANALYSIS OF THE ENVIRONMENTAL IMPACT OF THE NOISE OF TRAFFIC IN TERMINALS OF URBAN COLLECTIVE TRANSPORT: A STUDY OF CASE IN THE MUNICIPAL DISTRICT OF FORTALEZA

Roger Cajazeiras Silveira 12 September 2008 (has links)
O processo de urbanizaÃÃo das grandes cidades, o aumento das viagens motorizadas e o acrÃscimo das atividades industriais tÃm agravado as externalidades ambientais, em particular a poluiÃÃo sonora. Essa poluiÃÃo incomoda à populaÃÃo, contribui para a degradaÃÃo da qualidade de vida, tendo reflexos em todo o organismo e nÃo somente no aparelho auditivo, mas, tambÃm, à um problema de saÃde pÃblica. A estratÃgia de terminais de integraÃÃo objetiva facilitar o deslocamento da populaÃÃo nas grandes cidades, entretanto concentra a operaÃÃo de Ãnibus num pequeno espaÃo, o que gera um elevado nÃvel de ruÃdo. Esse estudo propÃe diagnosticar o nÃvel de ruÃdo dentro dos terminais na cidade de Fortaleza, comparÃ-los com a legislaÃÃo vigente e investigar os parÃmetros que influenciam nos nÃveis de ruÃdo / The process of urbanization of large cities and the increase of the number of motorized trips and the increment of the industrial activities has been worsening the environmental impacts, in particular the noise pollution. That pollution troubles the population, contributes to the degradation of life quality and is also a public health problem. The strategy of using integration terminals aims to facilitate the transportation of the population in those cities. However, there is a concentration of the bus operation on a relatively small space, what generates high noise levels. This research intends to diagnose the noise level inside the terminals in the city of Fortaleza. The results will be compared with the existing legislation and the parameters that influence these levels will be studied

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